In our book [1], we proposed some stability test theorems for linear time-delay system.
To verify our stability test theorems and others' stability test algorithms [2], we provide this simulation program of time-delay systems.
You can use the program, to find that the results of [2] are incorrecct.
The following example is taken from the case 1 of [2], where [2] claimed to found a stable region for the time-delay system of case 1,however, the simulation shows that the time-delay system of case 1 is unstable,
dx(t)/dt=Ax(t)+B1x(t-t1)+B2x(t-t2)+B3x(t-t1)+B4x(t-t4)
with delay parameters: t1=.4;t2=.5; t3=.169;t4=0.26.
Thus, the main results of [2] are incorrect.

Reply to the comments of Rifat Sipahi:
Most of stability test algorithms are sufficient condition for time-delay systems. To verify the conservatism of the algorithms we need some examples of time-delay systems. We are interested in the recent new stability test algorithms including your algorithm in [2].
However, we disappointed that [2] claimed to found a stable region for the time-delay system of case 1, our simulation shows that the time-delay system of case 1 is unstable in fact. It is possible for the example in [2] to mislead readers of IEEE Trans AC.